D4.2 - pollution (1j)

Question 1

what is biomagnification?

Answer 1

in biomagnification increased concentrations of toxins accumulate in the tissues of consumers at each successive trophic level

Question 2

what is the process of biomagnification?

Answer 2

1. the toxins enter the environments and are taken up by organisms in a lower trophic level
2. the lower trophic level organisms are eaten by consumers, passing the toxin up the food chain
3. each organism in a trophic level typically consumers many organisms from the previous trophic level
4. at each level, the toxin accumulates as it is not easily excreted and degrades very slowly, so the uptake rate is greater than the rate of loss
5. there are negative effects on the organisms at higher trophic levels

Question 3

how can we distinguish between bioaccumulation and biomagnification?

Answer 3

bioaccumulation - occurs within each individual organism over time

biomagnification - occurs by comparing trophic levels, as matter is transferred between them

Question 4

what is an example of the biomagnification of mercury?

Answer 4

microorganisms at the lower trophic levels of aquatic food chains convert mercury to methyl mercury, which accumulates in organisms of higher trophic levels through biomagnification

Question 5

what are the properties of mercury?

Answer 5

mercury is a naturally occurring element, but food chains demonstrating mercury biomagnification are almost always located near an industrial source of mercury

Question 6

what are the negative effects of mercury?

Answer 6

at high concentrations, mercury causes neurological damage, impacting organisms at higher trophic levels, including humans who eat contaminated fish

Question 7

what is DDT?

Answer 7

DDT is an insecticide, which is used to reduce populations of disease vectors (eg, mosquitos carrying malaria) and so reduce disease prevalence

Question 8

what led to the biomagnification of DDT?

Answer 8

DDT was sprayed from aircraft and some entered aquatic environments through run-off

Question 9

what are the consequences of the biomagnification of DDT?

Answer 9

biomagnification of DDT in food chains has a negative impact on the health of top predators
- (eg) causing thin eggs shells (due to altered metabolism of calcium) and reducing reproductive success in birds of prey

Question 10

why are plastic persistent in the natural environment?

Answer 10

they are not biodegradable

Question 11

what is macroplastic pollution?
what are some examples?

Answer 11

macroplastic pollution is plastic debris of more than 5 mm

Question 12

what are examples of macroplastic pollution?

Answer 12

• entanglement in plastics can lead to the death of marine birds, such as gulls
• ingested plastics may break down to form microplastics within the ingesting organism
• floating plastic debris can block sunlight, preventing photosynthesis and so reducing primary production by algae and phytoplankton

Question 13

what are the consequences of microplastic pollution?

Answer 13

• birds are unable to fly or swim for food
• birds cannot escape predators
• birds are strangled and suffocate
• birds drown

Question 14

what is microplastic pollution?
what are some examples?

Answer 14

microplastic pollution is plastic debris of less than 5 mm, some of which has resulted from mechanical breakdown of macroplastic, and some which is added to cleansers as exfoliation

Question 15

what are some examples of microplastic pollution?

Answer 15

• ingested plastics can cause problems for marine birds
• toxic microplastics in seawater may be ingested by organisms in lower trophic levels (eg, filter feeders). The microplastics then biomagnify, poisoning wildlife in higher trophic levels

Question 16

what are the consequences of microplastic pollution?

Answer 16

• filling up the stomachs of young birds so they feel full and starve to death
• damage the digestive system but cutting the oesophagus, stomach and/or intestines, leading to internal bleeding
• blocking passage of food, causing starvation
• causing choking, so birds cannot breathe
• containing or decomposing to form toxic chemicals, poisoning birds